This invention relates to hydraulic motors or pumps and more particularly to seals for use in such apparatus.
The seal of this invention is particularly useful with vane type hydraulic pumps or motors including a housing, a rotor received within said housing having radially reciprocating vanes therein which engage and ride on a fixed stator or cam ring surrounding the rotor. The seal is useful with pumps and motors of the prior art. Motors and pumps of the prior art comprise a housing, a vane-carrying rotor received in said housing and a stator or cam ring encircling said rotor. An elongated bore extends axially and centrally through said housing and rotor and receives a sleeve which is drivingly engaged by said rotor. The sleeve is journaled for rotation at its end portions through suitable bearing means disposed in recessed offsets in the bore and receives a power take-off shaft.
For purposes of this application, the apparatus in which the seal of this invention is employed is described as a motor though it is to be understood that it is equally adaptable to and effective in hydraulic pumps of similar structure. For many uses of fluid translators of the type described herein, it is advantageous to install the motor in a manner in which the shaft which is drivingly engaged by the rotor, is a permanent part of the mechanism being driven and not a part of the motor. For these types of field applications, sealing is independent of the shaft.
In the aforementioned field, and in most of the motors of the prior art employing a vane-carrying rotor, the leakage along the opposite side walls of the rotor and rotor chamber is a common problem requiring the use of seals at some point in the side wall surfaces of the rotor housing or requiring a shaft and shaft seal which is a permanent and integral part of the motor. The most common type of side wall seal employed is a four-lobed, homogeneous, annular seal. The four-lobed seals are received in annular recesses either in the rotor wall or in the side wall of the rotor chamber. The seal of this invention to be described below is designed to replace the aforementioned seals and to effectively prevent leakage from the area between the side walls of the rotor and the opposed surface of the rotor chamber. One of the main drawbacks to using four-lobed seals in this particular area is that the pressure from the fluid tends to distort the four-lobed seal in the annular recess and, in fact, move a part of the ring out of sealing engagement with the opposite surface. Methods can be devised to reduce O-ring distortion. However, side wall seals of this type lend to continually seep a small amount of fluid due to surface imperfections in the annular groove or in the side walls which the O-rings engage. This leakage tends to increase as pressure increases. Further, seals of the prior art are generally not readily accessible and their dispositIons oftentimes require the complete disassembly of the housing and removal of the rotor.
It is an objective of this invention to provide a hydraulic motor seal which overcomes the above-mentioned drawbacks of the prior art.
More particularly, it is an objective of this invention to provide a seal which is independent of a shaft.
It is a further objective of this invention to provide a seal which will result in essentially no leakage.
It is a further objective of this invention to provide a seal which is forced into tighter sealing engagement as the fluid pressure acting against it increases.
It is a further objective of this invention to provide a seal which is readily accessible for replacement or repair as the need arises.